This invention relates to heat pump heating/cooling systems. More particularly, this invention relates to heat pump heating/cooling systems especially suited for use in northern climates.
Heating and air conditioning in northern climates can present a challenge. Northern climates are characterized by cold, dry air in the winter months, and warm, humid air in the summer months. The outdoor temperature in the winter months can be extremely cold. For this reason, the energy required to heat a house in winter is generally much greater than the energy required to cool the same northern climate house in the summer.
Known heat pumps are generally air source heat pumps, water (ground) source heat pumps, water-to-air heat pumps, or water-to-water heat pumps. Generally air source heat pumps employed in northern climates do not meet the desired heating requirements.
During the winter months in the northern climates, known air source heat pumps convert relatively cold outdoor air to heated air for use inside a structure, for example homes and offices. As an example, when the outdoor ambient air temperature is approximately 20 degrees below zero Fahrenheit, approximately 60,000 BTU/hr of heating capacity is required to heat a typical home. Known air source heat pumps capable of producing 60,000 BTU/hr of heating during the winter months will inherently provide about four times the energy capacity required for cooling during the summer months. That is to say, the capacity to heat in the winter greatly exceeds the cooling capacity required during the summer, such that an imbalanced and inefficient cooling capacity ratio is provided by known heat pumps.
In addition, known air source heat pumps common in the northern climates experience a drastic drop-off in heating efficiency in the winter months. Specifically, the cold winter air is dense, and pulling heat energy from the dense air is challenging. That is to say, auxiliary energy (i.e., additional energy) is required to proportionally heat the colder outdoor air common in the northern climates for heating use inside structures. The auxiliary energy is supplied at an efficiency of 100% or less, such that the use of auxiliary heating results in a drop-off in the system heating efficiency in the winter months.
Moreover, in many instances coils employed with known cooling units will not function properly for most northern climate heat pump installations. This is because the coils experience increased frost build up that forms icing on the coils, thus reducing air flow heat exchange across the coils.
For these reasons, known heat pumps commonly employed in heating and cooling northern climate structures have at least two disadvantages. The first disadvantage is that traditional heat pumps provide much greater cooling capacity than is required in the summer months because the heating capacity needed to meet the heating needs of the winter months is so much larger than that needed for cooling. Secondly, the heating efficiency derived from known heat pumps drastically drops off for cold outdoor ambient air temperatures. Therefore, a need exists for a heating/cooling system capable of efficiently and quickly heating an indoor northern climate structure and cooling via air conditioning the same structure in the summer months.